Splined shaft and wheel retained thereon by spring and hub element

ABSTRACT

A construction toy including a splined shaft and a wheel element nonrotatably fitting thereon and retained by a spring ring which grips the shaft. A hub element is detachably secured to the wheel, with the spring occupying a recess between wheel and hub elements to limit their movement on the shaft. A. The Problem Small children playing with mechanical toy building sets often have difficulties in securing pinions, pulleys, discs and similar wheel elements on shafts when building vehicles or other mechanical devices. Fastening such wheel elements on the shafts generally requires the use of tools or accessories which are difficult to handle for small children. B. The Solution Two essential features are required for solving this problem, and the invention consists in the combination of these features: A. To provide a shaft having a noncircular cross section and wheel elements having a complementary hole, so as to enable the child to mount the wheels on the shaft by pushing them thereon from one end, thereby fixing the wheels on the shaft so as to prevent relative rotational movement. B. To provide a frictional fit between the shaft and the wheels so that axial displacement can only be effected by overcoming the friction therebetween. To this end a cylindrical recess is provided in the wheel element surrounding the central hole therein and an annular spring is located in the cylindrical recess in such a manner as to exert a radial pressure against the shaft, thereby increasing the frictional resistance against axial displacement of the wheels relatively to the shaft. The functioning of this spring is automatic and requires no skill or attention on the part of the user. C. The shaft may be tapered at one end, so as to facilitate the mounting of the wheels. D. The width of the cylindrical recess or cavity within the wheel is greater than the thickness of the spring to prevent the spring from being jammed within the cylindrical recess. E. The cylindrical cavity or recess is closed so as to totally enclose the annular spring by means of a hub element assembled with the side of the wheel.

United States Patent Christiansen 1 Feb. 1, 1972 [72] Inventor: GodtfredKirk Christiansen, Billund,

Denmark [73] Assignee: Interlego A.G., Zug, Switzerland 22 Filed: Jan.29, 1970 [21] Appl. No.: 6,718

[30] Foreign Application Priority Data Feb. 3, 1969 Denmark ..573/69[52] US. Cl ..46/23, 46/31, 46/221, 287/52.05, 301/112 [51] Int. Cl...A63h 33/10 [58] FieldofSearch ..46/16, 17, 23,31,206, 221; 301/1, 112;287/5205 [56] References Cited UNITED STATES PATENTS 3,566,536 3/ 1971Baynes et al ..46/221 3,553,882 l/l97l Meates ....46/23 X 2,539,3871/1951 Alden ....30l/112 3,396,554 8/1968 Westercamp.. 287/5205 X806,872 12/1905 Clark ....30l/1 UX 2,186,188 l/1940 Allen ..46/173,236,004 2/1966 Christiansen ....46/ 23 FOREIGN PATENTS OR APPLICATIONS649,440 l/1951 Great Britain ..287/52.05

Primary ExaminerF. Barry Shay Attorney-Stevens, Davis, Miller & Mosher[57] ABSTRACT secured to the wheel, with the spring occupying a recessbetween wheel and hub elements to limit their movement on the shaft.

A) THE PROBLEM Small children playing with mechanical my building setsoften have difficulties in securing pinions. pulleys. discs and similarwheel elements on shafts when building vehicles or other mechanicaldevices. Fastening such wheel elements on the shafts generally requiresthe use of tools or accessories which are difficult to handle for smallchildren.

B) THE SOLUTION Two essential'features are required for solving thisproblem, and the invention consists in the combination of thesefeatures:

A constructionjoy including asplined shaft and a wheel elementnonrotatably fitting thereon and retained by a spring a. To provide ashaft having a noncircular cross section and wheel elements having acomplementary hole, so as to enable the child to mount the wheels on theshaft by pushing them thereon from one end, thereby fixing the wheels onthe shaft so as to prevent relative rotational movement.

b. To provide a frictional fit between the shaft and the wheels so thataxial displacement can only be effected by overcoming the frictiontherebetween. To th is end a cylindrical recess is provided in the wheelelement surrounding the central hole therein and an annular spring islocated in the cylindrical recess in such a manner as to u exert aradial pressure against the shaft, thereby increasingthe frictionalresistance against axial displacement of the wheels relatively to theshaft. The functioning of this spring is automatic and requires no skillor attentio n on the part of the user.

cTT he shaft may betapered at one end, so as to facilitate the mountingof the wheels.

d. The width of the cylindrical recess or cavity within the wheel isgreater than the thickness of the spring to prevent the spring frombeing jammed within the cylindrical recess.

e. The cylindrical cavity or recess is closed so as to totally enclosethe annular spring by means of a hub element assembled with the side ofthe wheel.

ring which grips the shaft. A hub element is detachablylClaims,3DrawingFigures 3/ G O C) i 22 11,13 0 C) Of a! SPLINED SHAFTAND WHEEL RETAINED THEREON BY SPRING AND HUB ELEMENT This inventionrelates to mechanical toy building sets comprising elements preferablymade of molded thermoplastic material and including bearing elements,shaft elements adapted to be rotatably mounted therein and wheelelements adapted to be mounted on the shaft elements for rotationtherewith. More particularly, the invention relates to a wheel prises acylindrical recess or cavity 25 in the side face 22 and surrounding andcoaxial with the hole 24, said recess being adapted to receive theannular spring 26 and to form an enclosed annular groove in the wheelelement 20 when the latter is assembled with the hub element 30.

The hub element 30 comprises a cylindrical center portion 31 having acentral hole 34 of identically the same shape as the hole 24 in thewheel element 20 and a cross-shaped'disc portion having four branches 32each carrying a stud 33 proand Shaft assembly Such building Setsincluding fastening jecting from the back face thereof and adapted to beinserted means for mounting the wheel elements on the shafts in anydesired position so as to exclude any rotational movement relativelythereto but permitting an axial displacement against the frictional fitbetween the wheel and'the shaft. It should be noted that, in thiscontext, the works wheel element" refer to any element of circular ordisclike shape such as running or driving wheels, pinions, pulleys andsimilar elements adapted to be mounted on shafts for building vehicles,gears, power transmission systems or the like.

The principal object of the invention is to provide simple, efiicientand inexpensive fastening means which will enable even quite smallchildren to fix the wheel elements safely and securely on the shaftelements without any requirements for skill and accuracy and without anyuse of tools or accessories. It has been found through many years ofpractical experience that the fulfillment of these conditions is ofdecisive importance to the utility and success of such toy buildingsets: the basic requirement is that the toy must be childproof, and itshould be observed that this is by no means achieved by simply copyingreal machine elements on a reduced scale, In fact, in many cases athorough study of child psychology and behavior is required for theconstruction of toy elements which are completely childproof.

In the case of the present invention, the object of providing achildproof wheel and shaft assembly has been achieved by the combinationof features set forth in the claims and explained in details withreference to the embodiment illustrated in the drawings, wherein:

FIG. 1 is an exploded perspective view showing the components of thewheel and shaft assembly according to the invention,

FIG. 2 is an axial sectional view showing the wheel element mounted onthe shaft and operatively associated therewith,

FIG. 3 is a view similar to FIG. 2 showing a pair of wheel elementsmounted on the shaft at either side of a bearing element in which theshaft is rotatably mounted.

Referring to the drawings and more particularly to FIG. 1 thereof, itwill be seen that the components of the wheel and shaft assemblycomprise the following main elements:

a shaft element, generally designated as a wheel element, generallydesignated as a hub element, generally designated as an annular spring26.

The shaft 10 is provided with four lengthwise extending grooves 11forming between them four ridges or beads 12 so as to provide for across-shaped cross section 14 of the shaft. One end of the shaft 10 isslightly tapered as shown at 10a in FIG. 1 so as to facilitate themounting of the wheel element 20 by pushing it on to the shaft from oneend thereof. The external surface 12a of the ribs or ridges 12 are ofcylindrical shape constituting fractions of a cylindrical surfaceinterrupted by the grooves 11 and providing for rotational mounting ofthe shaft within a bearing element as shown in FIG. 3. Finally, the ribsor ridges 12 may be provided with a plurality of grooves 13 extending inthe transverse direction of the shaft. The function of these grooves 13will be explained in the following.

The wheel element 20 shown in FIG. 1 comprises a cylindrical surface 21which may be provided with teeth (not shown) if the wheel element is apinion or with a groove if the wheel element is a pulley. For the sakeof simplicity, the wheel element is shown as a disc having a plaincylindrical face 21 and annular side face 22 comprising four holes 23and a central hole 24 of substantially the same configuration as thecross section 14 of the shaft 10. Finally, the wheel element cominto thefour holes 23 of the wheel element 20 so as to provide coupling meansfor interconnecting the wheel 20 and the hub 30 when the annular spring26 has been inserted in its groove 25. The depth of this groove, i.e.,its extension in the axial direction of the assembly should be slightlylarger than the thickness of the annular spring 26 soas to allow for aslight axial displacement of the wheel element relatively to the springwhen the latter is clamped around the shaft within the groove 25. Infact, it will be appreciated that, if the spring 26 could be clamped orpinched between the hub and wheel elements, its spring function would beeliminated and it could no longer function as a stop preventing orhampering axial displacement of the wheel on the shaft. On the otherhand this function may be increased by provision of the grooves 13 forreceiving the spring 26 as shown in F IG. 2.

FIG. 3 shows a pair of wheel elements 20A and 20B mounted adjacent abearing element 40 at either side 40a and 40b thereof. The shaft 10carrying the wheels 20A and 20B is rotatably mounted within the bearing-40 by means of the cylindrical portions 12a of the ribs 12, thediameter of which substantially corresponds to the internal diameter ofthe bearmg.

The purpose of FIG. 3 is to show how the particular arrangementaccording to the invention tends to make the assembly completelychildproof.

By using any of the previously known fastening means for fixing thewheels 20A and 20B adjacent the bearing 40, the child might very wellrisk that the wheels would be fixed so closeto the bearing as to beclamped against its surface thus preventing rotation of the shaft. Suchfastening means, therefore, are not childproof.

On the other hand, when using the assembly according to this invention,the child may simply push the wheel elements 20A and 208 along the shaftuntil their side faces touch the sides of the bearing 40. The slightplay of the wheel element relatively to the spring element 26 graspingthe shaft will always allow for sufficient axial displacement to preventany blocking of the wheels against the sides of the bearing.

lclaim:

1. In a toy building set, a wheel and shaft assembly comprising thecombination of the following components made by injection molding of athermoplastic material:

a. A splined shaft element having a plurality of axially extendinggrooves forming ribs therebetween, said ribs having cylindrical outersurfaces coaxially disposed with respect to the shaft;

b. An internally splined wheel element fitting the shaft element, so asto be slidably, but nonrotatably secured thereto, said wheel elementcomprising a disc-shaped member having at least one plane side face, acentral bore in said plane side face defining a cylindrical recess insaid disc-shaped member;

c. An annular spring fitting into said cylindrical recess, the width ofsaid annular spring being less than the depth of said cylindricalrecess; and

d. An internally splined hub element fitting the shaft element so as tobe slidably, but nonrotatably mounted thereon adjacent the cylindricalrecess in the discmember, thereby defining a closed cylindrical cavityin said disc enclosing the said annular spring, said disc and hubelements being provided with means for mutually interlocking them, saidspring being of a size such that, when said wheel element, spring andhub element are mounted on said shaft element, said spring exerts aradial pressure on said shaft element while preventing said wheelelement and hub element from sliding past said spring.

1. In a toy building set, a wheel and shaft assembly comprising thecombination of the following components made by injection molding of athermoplastic material: a. A splined shaft element having a plurality ofaxially extending grooves forming ribs therebetween, said ribs havingcylindrical outer surfaces coaxially disposed with respect to the shaft;b. An internally splined wheel element fitting the shaft element, so asto be slidably, but nonrotatably secured thereto, said wheel elementcomprising a disc-shaped member having at least one plane side face, acentral bore in said plane side face defining a cylindrical recess insaid discshaped member; c. An annular spring fitting into saidcylindrical recess, the width of said annular spring being less than thedepth of said cylindrical recess; and d. An internally splined hubelement fitting the shaft element so as to be slidably, but nonrotatablymounted thereon adjacent the cylindrical recess in the disc-member,thereby defining a closed cylindrical cavity in said disc enclosing thesaid annular spring, said disc and hub elements being provided withmeans for mutually interlocking them, said spring being of a size suchthat, when said wheel element, spring and hub element are mounted onsaid shaft element, said spring exerts a radial pressure on said shaftelement while preventing said wheel element and hub element from slidingpast said spring.